A broadband differential confocal method that exploits novel double-slit chromatic confocal microscopy was developed for one-shot microscopic 3D surface measurement. In situ automated optical inspection to generate microscopic surface profiles has become extremely important for ensuring strict geometric compliance in precision manufacturing. An innovative optical configuration was developed to generate a pair of orthogonally polarized incident light beams, and a pair of the conjugate light beams was detected using two slits of different widths at the corresponding conjugate imaging locations of the incident beams. A sub-micrometer depth measuring repeatability can be achieved for the one-shot reconstruction of 3D surface profiles.